Although many different designs of can openers are known, very few work really satisfactorily. In many instances, the cutting edge is liable to become jammed and a ragged cut given which can be dangerous to the user. Also small filings of metal may be generated which contaminate the contents of the can.
Our co-pending European patent application No. 84304750.7 describes a hand-held can opener intended to provide a cut around the wall of the can below the lid and rim which are severed by the cut from the rest of the can, the can opener comprising a pair of body members pivotally joined to one another, each body member having an integrally-formed handle extending generally away from the point of pivoting and movable between a more open position and a more closed position, the handles being intended to be grasped by one hand of the user in the more closed position, a spindle to which is attached a driving wheel to be brought into contact with the lip of the lid of a can, the spindle being manually rotatable to cause the driving wheel to orbit the can opener relatively around the top of the can, a cutting wheel which, in an operating cutting position, forms a nip with the driving wheel so that the cutting edge of the cutting wheel is forced to penetrate through the wall of the can and provide a cut around the can as the opener orbits relatively around the can, a mounting plate slidably supported by one of the body members and on which the cutting wheel is rotatably mounted, the sliding plate being movable between the operating cutting position where the driving wheel forces the cutting edge to penetrate the can wall and an inoperative position where the cutting wheel is moved, e.g. substantially radically relative the axis of rotation of the cutting wheel, away from the cutting wheel, and cam means for moving the plate and the supported cutting wheel to the cutting position as the handles are pivoted towards the more closed position and moving it away to its inoperative position when the handles are pivoted away from that said limit of pivoting towards the more open position.
Such a can opener has been found to give a good clean cut without ragged edges and substantially without the formation of dangerous metal filings. In addition, the can opener can usually operate successfully even if the can is quite seriously damaged and dented. Further the can opener will work both on conventional cylindrical shaped tins and on tins of other shapes, e.g. oval or square.
We have however encountered a problem with such a can opener in that when opening cans which are particularly tough the two handles may twist relative one another and cause the body members to open up sufficiently for the cam means and the sliding plate to become disengaged. It is therefore an object of the present invention to eliminate this possibility.